Move VS projects back to dmd/src/vcbuild

[rainers]

The VS projects are complementing the makefiles so they should not be part of the ddmd sources, but on the same folder level as the makefiles. Minor other changes:

• update file references to new folder structure
• added missing new source files
• changed the output directory from sub folder "generated" to the new common output folder (subfolder "Windows" there)
• changed project name and output file name to "dmd" for better consistency (see also Visual studio solution should output a executable called "dmd.exe" #6506)

As this also moves files like msvc-lib.d and msvc-dmc.d, Digger might also be affected (or fixed).